Positive station module locking mechanism for expandable irrigation controller

ABSTRACT

A modular expandable irrigation controller has controls for manual entry or selection of a watering program and a memory for storing the watering program. A processor executes the stored watering program and controls one or more station modules each including a station module circuit for energizing at least one solenoid actuated valve in accordance with the watering program. The irrigation controller has a plurality of receptacles for each removably receiving a station module and for providing an operative connection to the processor. A manually movable locking member is grasped and moved between UNLOCKED and LOCKED positions to positively secure each station module in a corresponding receptacle.

FIELD OF THE INVENTION

The present invention relates to electronic irrigation controllers thatcontrol valves which supply water to sprinklers, and more particularly,to modular expandable irrigation controllers.

BACKGROUND OF THE INVENTION

In many parts of the world due to inadequate rainfall it is necessary atsome times during the year to artificially water turf and landscaping.An ideal irrigation system for turf and landscaping should utilize aminimum number of valves, supply lines and sprinklers. Preferably thevalves should be turned ON and OFF by an inexpensive, yet reliableelectronic irrigation controller that is easy to program and can carryout a wide variety of watering schedules. The goal is to uniformlydistribute the optimum amount of water over a given area. Rotor typesprinklers have largely displaced older impact type sprinklers inapplications where large expanses of grass are watered, such as golfcourses, due to the fact that the former are more reliable, quieter, anddistribute water on a uniform and controlled basis. Spray typesprinklers, rotary stream sprinklers, bubblers and drip irrigationdevices are also frequently used in residential and commercialirrigation systems. When an irrigation system is designed and/orinstalled the type, placement and precipitation rates for each of thesprinklers are pre-selected. The optimum precipitation rate provided byeach sprinkler should preferably fall within plus or minus one-quartergallons-per minute (GPM). The amount of water supplied by each sprinkleris largely determined by the size and configuration of its nozzleorifice(s), although variations result from fluctuations in waterpressure that cannot be fully negated with regulators.

Preferably an irrigation controller should have the capability oftemporarily terminating its watering program if sufficient rain occursbased on signals inputted from a rain sensor. See for example, U.S. Pat.No. 5,097,861 granted Mar. 24, 1992 of Hopkins et al. entitledIRRIGATION METHOD AND CONTROL SYSTEM, assigned to Hunter Industries,Inc., the assignee of the subject application, the entire disclosure ofwhich is hereby incorporated by reference. On suitable rain sensor forthis purpose is disclosed in pending U.S. patent application Ser. No.10/053,100 filed Oct. 26, 2001 of Paul A. Klinefelter et al. entitledQUICK SHUT-OFF EXTENDED RANGE HYGROSCOPIC RAIN SENSOR FOR IRRIGATIONSYSTEMS, also assigned to Hunter Industries, Inc., the entire disclosureof which is hereby incorporated by reference.

Residential and commercial irrigation systems typically include one ormore solenoid operated valves that are turned ON and OFF by anelectronic irrigation controller. The valves admit water to varioussubterranean branch lines usually made of PVC pipe that typically haveseveral sprinklers connected to risers coupled to the branch lines atspaced intervals. Each combination of a solenoid valve and itsassociated sprinklers is referred to in the irrigation industry as astation or zone. A modern electronic irrigation controller typicallyincludes a microprocessor and separate memory, or a micro-computer withon-chip memory, that stores and executes one or more watering programs.The watering programs can be pre-programmed by the user via push buttonand/or rotary controls. The controller usually has an LCD or otherdisplay to facilitate programming by the user. Often the controller willrevert to a default watering program in the case of a power failure. Themicroprocessor controls the solenoid valves via suitable drivers andswitching devices. The valves are opened and closed by themicroprocessor in accordance with the pre-programmed run and cycle timesfor each of the stations.

Over the past decade, modular expandable irrigation controllers havegained increasing popularity. In these controllers, the base portion ofthe system contains the microprocessor and user actuated controls. Eachstation is then controlled by a corresponding station module whichcomprises a plastic housing that encloses and supports a station modulecircuit, as well as wire connection terminals for connecting wires to aplurality of solenoid actuated valves. Typically each station module canindependently control more than one solenoid actuated valve, i.e.,station. The station modules contain pins, sockets, card edge connectorsor some other standard form of electro-mechanical connectors forallowing them to be inserted into slots or receptacles in either thehousing that contains the microprocessor or a separate back panel hingedto the microprocessor housing. The advantage of this configuration isthat the controller need only be equipped with the minimum number ofstation modules that can control the total number of stations. Thus, forexample, an irrigation system may have only three zones, requiring onlya single station module, while another may have twelve stations whichmight require four station modules. Considerable cost savings are thusachieved. Moreover, if an irrigation system expands after initialinstallation because the landscaping has increased, additional stationmodules can be added. In some modular expandable irrigation systems thebase unit is capable of controlling a minimal number of stations withoutrequiring the addition of any station modules. In others, such as theICC™ and Pro C™ irrigation controllers manufactured and sold by HunterIndustries, Inc., at least a power module and one irrigation stationmodule must be plugged into the controller in order to operate anystations or zones.

When the station modules are plugged into the receptacles of a modularexpandable irrigation controller they are mechanically supported and anelectrical connection is made between the microprocessor and the driver.The station modules can be removed and replaced if damaged, for example,during a lightening strike. It has been conventional to use plasticspring members or elements to hold the station modules in place in theirrespective receptacles or slots. However, such springs often requireconsiderable force to be exerted by the user, both during installationand withdrawal of the station modules. The spring members can also breakand difficulties have been encountered in ensuring that a complete andpositive electrical connection is both achieved and maintained. In somecases, station module installation can lead to breakage in the metalpins or metal leaf spring contacts used to make the electricalconnection.

Accordingly, it would be desirable to provide a modular expandableirrigation controller with improved station module mating to minimize oreliminate the foregoing problems.

SUMMARY OF THE INVENTION

In accordance with the present invention a modular expandable irrigationcontroller has controls for manual entry or selection of a wateringprogram and a memory for storing the watering program. A processorexecutes the stored watering program and controls one or more stationmodules each including a station module circuit for energizing at leastone solenoid actuated valve in accordance with the watering program. Theirrigation controller has a plurality of receptacles for each removablyreceiving a station module and for providing an operative connection tothe processor. A manually movable locking member secures each stationmodule in a corresponding receptacle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an enlarged perspective view of a station module of a firstembodiment of our invention.

FIG. 2 is a fragmentary perspective view of the station module of FIG. 1inserted into a back panel of the first embodiment.

FIG. 3 is an enlarged fragmentary perspective of the rear side of theback panel illustrating the engagement of locking tab of the firstembodiment with the back panel.

FIG. 4 is a top plan view of a second embodiment of the presentinvention.

FIG. 5 is a vertical sectional view taken along line 5-5 of FIG. 4.

FIG. 6 is an enlarged fragmentary perspective view illustrating therelationship of the locking slide bar of the second embodiment to fourmodules installed side-by-side in its bay when the locking slide bar isin its UNLOCKED position.

FIG. 7 is an enlarged fragmentary perspective view similar to FIG. 6 buttaken from a different angle and illustrating the relationship of thelocking slide bar of the second embodiment to four modules installedside-by-side in its bay when the locking slide bar is in its LOCKEDposition.

FIG. 8 is an enlarged vertical sectional view of the locking slide bartaken along line 8-8 of FIG. 5.

FIG. 9 is a greatly enlarged fragmentary view of the portion of thelocking slide bar circled in FIG. 8.

FIG. 10 is a block diagram of the overall irrigation controller circuitthat may be used in either of the first or second embodiments.

FIG. 11 is a schematic diagram of an exemplary circuit for one of thestation modules of the irrigation controller circuit of FIG. 10.

FIG. 12 is a schematic diagram of an alternate circuit for one of thestation modules.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1-3, in accordance with a first embodiment of ourinvention, a rectangular station module 10 has a pair of rigid(non-resilient) wedge-shaped tabs 12 and 14 that project from one endand a pivotable locking lever 16 that is mounted at the opposite end.The station module 10 is inserted into a receptacle such as 18 (FIG. 2)formed in the back panel 20 that is hinged to a separate housing (notshown) that contains the microprocessor. During the insertion of thestation module 10 into the receptacle 18, the left end of the stationmodule is first lowered into the receptacle 18 so that the wedge-shapedtabs 12 and 14 are inserted into corresponding side-by-side rectangularapertures in one end wall of the receptacle 18, which are similar to thetwo apertures 24 and 26 in the opposite end wall. The right end of thestation module 10 is then lowered into the receptacle 18. At this timepins (not shown) on the back side of the station module 10 are pluggedinto corresponding holes in a female electrical connector 22 toestablish connection with a serial bus.

Once the station module 10 has been fully inserted into the receptacle18, the locking lever 16 is swung or pivoted ninety degrees from itsextended (unlocked) position illustrated in FIG. 1 to its retracted(locked) position illustrated in FIG. 2. This motion is translated via adrive shaft (not illustrated) journaled in a bearing sleeve in the endwall of the station module 10 to move a planar locking tab 28 (FIG. 3)underneath the back panel 20. The various parts are dimensioned toprovide a snug or tight fit when the locking lever 16 is moved to itslocked position. Thus, the station module 10 is locked and held in placewithin the receptacle 18 via the wedge-shaped tabs 12 and 14 and theplanar locking tab 28. The station module 10 can be removed from thereceptacle 18 by swinging the locking lever 16 to its unlocked positionand first lifting the right end of the station module to unplug its pinsfrom the connector 22 and then lifting the left end of the stationmodule to remove the wedge-shaped tabs 12 and 14 from theircorresponding apertures in the left end wall of the receptacle 18. Animportant aspect of the controller illustrated in FIGS. 1-3 is that thestation module 10 will fit in the receptacles of an older design. Inother words, the station module 10 is backward compatible with anoriginal commercial design of the controller.

A second embodiment of our invention is illustrated in FIGS. 4-9.Referring to FIG. 7, female electrical connectors 29 in the ends ofthree box-like station modules 30, 32 and 34 receive corresponding cardedge connectors such as 36 (FIG. 5) with mating electrical contacts. Thestation modules 30, 32 and 34 are received in side-by-side fashion in abay formed in a rectangular back panel 38 (FIG. 4) that is separate fromthe housing (not illustrated) that encloses the microprocessor. Alarger, fourth box-like power module 40 (FIG. 6) plugs into the bay ontoits own card edge connector and drives the pump master valve and thefirst three station modules 30, 32 and 34. The upper sides of themodules 30, 32, 34 and 40 each have an upstanding projection 42 (FIG.6). A locking slide bar 44 (FIG. 8) with a V-shaped gripping member 46extends above the bay and may be slid laterally (left and right) betweenan unlocked position illustrated in FIG. 6 and a locked positionillustrated in FIG. 7. A V-shaped bump 48 (FIG. 9) on the underside ofthe locking slide bar 44 can alternately register with differentV-shaped detents 50 and 52 formed in a cover 54 to hold the lockingslide bar 44 in its locked and unlocked positions. A pointed tab 56(FIG. 4) extending from the gripping member 46 alternately points toUNLOCKED and LOCKED indicia molded into the adjacent back panelstructure to indicate the module connection status to the user.

When the locking slide bar 44 is moved to the right in FIG. 4 to itslocked position, downwardly extending locking elements 58 (FIG. 5) movebehind the upstanding projection 42 on each of the modules 30, 32, 34and 40 to mechanically lock the modules in the bay and prevent theirwithdrawal. Any or all of the modules can be removed from the bay bymoving the locking slide bar 44 to the left in FIG. 4 to its unlockedposition so that the locking elements 58 are cleared from behind theprojections 42 to permit the modules to be pulled off of theircorresponding card edge connectors. The new modules 30, 32, 34 and 40 ofthe controller of FIGS. 4-9 are backward compatible with an earlieroriginal design of the controller because they simply plug into the cardedge connectors which hold them in place. The old modules of theoriginal controller are also forward compatible with the re-designedcontroller. FIGS. 6 and 7 also illustrate the upstanding projection 60of the old modules which is spaced laterally with respect to theupstanding projection 42 of the newer modules. The locking slide bar 44has alternate downwardly extending locking elements 62 (that arelaterally displaced from the locking elements 58) and move behind theupstanding projections 60 of the older modules to lock them in place.The old modules only have the upstanding projection 60 and the newmodules only have the upstanding projection 42, but both are shown inFIGS. 6 and 7 at the same time in order to illustrate the backward andforward compatibility.

Referring to FIG. 6, the upstanding projections 42 and 60 have atriangular cross-section the downwardly extending locking elements 58and 62 have a rectangular cross-section. The projections 42 and 60 areoriented so that if a user tries to insert a module, such as 32 into avacant receptacle in the bay formed in the rectangular back panel 38when the slide bar 44 is in its locked position, the slide bar 44 willbe forced to its unlocked position. This takes place as a result of theangled surfaces on the projections 42 and 60 colliding with and slidingthe locking elements 58 and 62 laterally. This automatic unlockingfeature prevents breakage of the projections 42 and 60 and/or thelocking elements 48 and 62.

Thus both embodiments of our invention each have a locking member thatis manually movable in the sense that it has with an outer portion thatis ergonmicially configured to be grasped by a user's hand and pivotedor slid to positively lock one or more station modules in place. Thelocking lever 16 has an enlarged outer portion 16 a (FIG. 1) that snapsover a small projection 17 in a cut-out corner 10 a of the stationmodule 10 to hold the lever in its locked position illustrated in FIG.2. The V-shaped gripping member 46 (FIG. 7) of the second embodiment isreadily grasped between the user's thumb and index finger. The positivemodule locking mechanism of our invention guards against partial orincomplete insertion of a station module that could lead to shorts thatwould make the station or zone inoperable. The user is given visual andtactile feedback indicating that a positive lock has been established inthe sense that each module has been fully inserted. In the case of thefirst embodiment illustrated in FIGS. 1-3 each station module 10 isindependently locked and unlocked. In the case of the second embodimentillustrated in FIGS. 4-9, a plurality of modules 30, 32, 34 and 40 aresimultaneously locked and unlocked with respect to their respectivereceptacles.

The back panel 20 (FIGS. 2 and 3) of the first embodiment is typicallymounted on a vertical wall of a building structure so that each stationmodule 10 is plugged in an removed in a generally horizontal directionaway from the user, and toward the user, respectively. The back panel 38(FIG. 4) of the second embodiment is also typically installed on avertical wall of a building structure so that the modules, such as 30(FIG. 6) are plugged in and removed in a horizontal direction, lateralrelative to the user. In other words, the back panel 38 is oriented sothat the modules are in a vertical column with the station module 34 ontop and the power module 40 on the bottom. In both the first and secondembodiments the weight of the modules cannot tend to unplug the same.

FIG. 10 is a simplified block diagram of the electronic circuit 100 thatmay be used with either of the preferred embodiments just described.Briefly, a microprocessor 102 executes a selected watering programstored in ROM 104 using RAM 106. The microprocessor 102 is coupledthrough an optional electro-optic isolator 108 and a serial bus 110 toone or more removable station modules 112 each including a stationmodule circuit 114 for energizing and de-energizing the solenoid of avalve (not illustrated) connected thereto via insulated wires (notillustrated). The electro-optic isolator 108 protects the microprocessor102 from damage if lightening should destroy one or more of the stationmodules 112, but it may be eliminated for cost savings.

The stripped inner ends of the wires that lead to the solenoid valvesare securred to conventioinal screw terminals 115 a (FIG. 1) on each ofthe modules 10 of the first embodiment or 115 b (FIG. 6) of the secondembodiment. The screw terminals 115 a are separated by upstandingdivider walls 11 (FIG. 1) to prevent contact between adjacent wires.Similarly, the screw terminals 115 b are separated by upstanding dividerwalls 41 (FIG. 6) to prevent contact between adjacent wires.

The valves may be of the type disclosed in U.S. Pat. No. 5,996,608granted Dec. 7, 1999 of Richard E. Hunter et al. entitled DIAPHRAGMVALVE WITH FILTER SCREEN AND MOVABLE WIPER ELEMENT, Inc.; U.S. Pat. No.6,079,437 granted Jun. 27, 2000 to Mathew G. Beutler et al. entitledDIAPHRAGM VALVE WITH FLOW CONTROL STEM AIR BLEED; and U.S. Pat. No.5,979,482 granted Nov. 9, 1999 of Loren W. Scott entitled REMOVABLECAPTIVE PLUNGER WITH CONTAMINATION PROTECTION, all assigned to HunterIndustries, Inc., the entire disclosures of which are herebyincorporated by reference.

The term “solenoid actuated valve” shall also encompass valves used inirrigation systems in which a pilot valve is not directly opened andclosed by a solenoid. These include hydraulically or pneumaticallyactuated valves which have a solenoid or its electrical equivalentsomewhere in the fluid system, and not necessarily next to the gatingvalve, for controlling the fluid pressure to open and close the valves.

A power supply 116 (FIG. 10) supplies the power needed to run themicroprocessor 102 and energize the solenoids of the valves. A removablepower module 117 contains current sensing resistors and has pump outputterminals. Power is routed from the power supply 116 through the powermodule 117 to the microprocessor 102 and to the station modules 112. TheDC power to run the microprocessor 102 and the logic circuitry insidethe station modules 112 is supplied by the power supply 116 through thepower module 117 to the microprocessor 102 and then back through thepower module 117 to the station modules 112. The AC power for switchingthe solenoid actuated valves ON and OFF is supplied from the powersupply 116 through the power module 117 to the station modules 112. Aset of manually actuated controls 118 are connected to themicroprocessor 102 for allowing a watering program to be entered,selected, altered, etc. with the aid of graphic and/or alphanumericsymbols shown on LCD 120. The controls may include a rotary switch, oneor more pushbuttons, one or more slide switches, one or more membraneswitches, one or more toggle switches, one or more insertable pins, aDIP switch, etc. Instead of using separate microprocessor 102, ROM 104and RAM 106, a single micro-computer with on-chip memory may beutilized. The preferred configuration of our irrigation controllerincludes a main PC board (not illustrated) which supports themicroprocessor 102, ROM 104, RAM 106, electro-optic isolator 108, serialbus 110 manual controls 118 and LCD 120. This main PC board is mountedinside a housing (not illustrated) which is connected via ribbon cableto a back panel such as 20 (FIG. 2) or 38 (FIG. 4) that is hinged to thehousing. The back panel 20 or 38 provides the receptacles for removablyreceiving the station modules 10 or 30, 32, 34.

A port (not illustrated) may be connected to the microprocessor 102 fordownloading a watering program that has been created on a personalcomputer and downloaded into a smart card, portable data shuttle orother removable media. See for example U.S. Pat. No. 6,088,621 grantedJul. 11, 2000 of Peter J. Woytowitz et al. entitled PORTABLE APPARATUSFOR RAPID RE-PROGRAMMING OF IRRIGATION CONTROLLERS, also assigned toHunter Industries, Inc., the entire disclosure of which is herebyincorporated by reference. Alternatively, the microprocessor couldreceive programming and/or commands from a master computer viahard-wired or wireless connection. The programming executed by themicroprocessor 102 can include a cleaning cycle which momentarily turnson each valve after completion of a run cycle to flush debris away fromthe valve seat. See U.S. Pat. No. 5,829,678 granted Nov. 3, 1998 ofRichard E. Hunter et al. entitled SELF-CLEANING IRRIGATION REGULATORVALVE APPARATUS, also assigned to Hunter Industries, Inc., the entiredisclosure of which is hereby incorporated by reference.

The microprocessor 102 controls a plurality of solenoid actuated valvesvia the corresponding station module circuit 114 (FIG. 11) which ismounted on a small PC board contained within the plastic housing of eachstation module 112. The station module circuit 114 includes amicrocontroller 122 that drives a switching device in the form of atriac 124 through a diode 126 and resistor 128. The triac 124 comprisestwo silicon controlled rectifiers (SCRs) connected in parallel andoppositely oriented to allow bi-directional control of a standardtwenty-four volt AC signal sent to the solenoid of a valve via terminal130. The control signal from the serial bus is applied to themicrocontroller 122 via serial data lead 132 while a nominal DC voltagesignal, such as five volts, is applied via another lead 134. Synchronousserial data is clocked into the microcontroller 122 from themicroprocessor 102 via clock lead 136. Twenty-four volt AC power issupplied from the power module 116 to the triac 124 via lead 138. In thepreferred embodiment of the station module circuit 114 triac 124, diode126 and resistor 128 are duplicated eight times so that one stationmodule 112 can independently control up to eight solenoid actuatedvalves (stations). The valves that supply water to the sprinklers canthus be independently opened and closed by the microprocessor 102utilizing the station module circuits 114 in accordance with theselected and/or pre-programmed run and cycle times for each of thestations. See also U.S. Pat. No. 5,444,611 granted Aug. 22, 1995 ofPeter J. Woytowitz et al. entitled LAWN AND GARDEN IRRIGATIONCONTROLLER, also assigned to Hunter Industries, Inc., the entiredisclosure of which is hereby incorporated by reference.

FIG. 12 is a schematic diagram of an alternate circuit 140 for one ofthe station modules 112′. Each station module 112′ has its own powersupply 142 that supplies a five volt DC signal to a microcontroller 144that can switch a triac 146 through diode 148 and resistor 150. Thestation modules 112′ each have three sets of the triac 146, diode 148and resistor 150 (not illustrated) for independently actuating threestations. The alternate station module circuit 140 (FIG. 12) receivesasynchronous serial data on serial data line 152. In other words, themicrocontroller 144 of the station module 112′ derives its clock signalfrom the serial data signal. Twenty-four volt AC power is supplied toeach power supply 142 inside each station module 112′ via lead 154.

Those skilled in the art will recognize that besides providing a newirrigation controller, we have also provided a novel method of expandinga modular irrigation controller. Our method includes the step ofproviding a microprocessor based irrigation controller with a pluralityof receptacles for each receiving a station module that is controlled bythe microprocessor to open and close a solenoid actuated valve connectedto the station module. Our method further includes the step of insertinga module into one of the receptacles. Our method involves the final stepof manually moving a locking member mounted adjacent the receptacle froman UNLOCKED position to a LOCKED position to secure the station modulein the adjacent receptacle.

While we have described two different preferred embodiments of ourmodular expandable irrigation controller with improved station modulelocking means, and a method of expanding a modular irrigationcontroller, it will be apparent to those skilled in the art that ourinvention can be modified in both arrangement and detail. For example,each station module 112 or 112′ could be configured for controlling onlya single station. Therefore, the protection afforded our inventionshould only be limited in accordance with the following claims.

1. A modular expandable irrigation controller, comprising: control meansfor manual entry or selection of a watering program; means for storingthe watering program; processor means for executing the stored wateringprogram and controlling one or more station modules each including astation module circuit for energizing at least one solenoid actuatedvalve in accordance with the watering program; means for providing aplurality of receptacles for each removably receiving a station moduleand for providing an operative connection to the processor; and means,including a manually movable locking member, for securing each stationmodule in a corresponding receptacle.
 2. The controller of claim 1wherein the movable locking member is a rotating lever.
 3. Thecontroller of claim 1 wherein the movable locking member is a slide bar.4. The controller of claim 1 wherein the station module circuit includesat least one switching device.
 5. The controller of claim 1 wherein thesecuring means further comprises UNLOCKED and LOCKED indicia and thesecuring means includes a pointer on the movable locking member thatmoves between first and second positions adjacent the UNLOCKED andLOCKED indicia, respectively.
 6. The controller of claim 1 wherein themeans for providing an electrical connection includes a femaleelectrical connector in each of the receptacles.
 7. The controller ofclaim 1 wherein the means for providing an electrical connectionincludes a card edge connector in each of the receptacles.
 8. Thecontroller of claim 1 wherein the movable locking member is a rotatinglever that is connected to a shaft that moves a locking tab underneath aportion of a back panel in which the receptacles are located.
 9. Thecontroller of claim 1 wherein the movable locking member is a slide barhaving a plurality of locking elements that move into and out ofobstructing relationship with at least one projection on each of thestation modules to simultaneously prevent and permit the removal of aplurality of station modules from their corresponding receptacles,respectively.
 10. The controller of claim 1 and further comprising meansfor providing a receptacle for removably receiving a power module andfor providing an electrical connection to the processor means.
 11. Amodular expandable irrigation controller, comprising: means for entry orselection of a watering program; a memory that stores the wateringprogram; a processor that executes the stored watering program andcontrols one or more station modules each including a station modulecircuit for opening and closing at least one valve in accordance withthe watering program; a plurality of receptacles each configured toremovably receive a station module and provide a connection to theprocessor; and a locking member mounted adjacent the receptacles andmanually moveable from an UNLOCKED position to a LOCKED position topositively secure the station modules in the receptacles.
 12. Thecontroller of claim 11 wherein the locking member is a rotating lever.13. The controller of claim 11 wherein the locking member is a slidebar.
 14. The controller of claim 11 and further comprising a pointer onthe locking member that moves between positions adjacent UNLOCKED andLOCKED indicia formed adjacent at least one of the receptacles.
 15. Thecontroller of claim 11 wherein each of the receptacles includes a femaleelectrical connector.
 16. The controller of claim 11 wherein each of thereceptacles includes a card edge connector.
 17. The controller of claim11 wherein the locking member is a rotating lever that is connected to ashaft that moves a locking tab underneath a portion of a back panel inwhich the receptacles are located.
 18. The controller of claim 11wherein the locking member is a slide bar having a plurality of lockingelements that move into and out of obstructing relationship with atleast one projection on each of the station modules to simultaneouslyprevent and permit the removal of a plurality of station modules fromtheir corresponding receptacles, respectively.
 19. The controller ofclaim 18 wherein the locking elements and the projection are configuredso that they will collide and move the slide bar to its UNLOCKEDposition if a user plugs the station module into an empty receptaclewhen the slide bar is in its LOCKED position.
 20. A method of expandinga modular irrigation controller, comprising the steps of: providing amicroprocessor based irrigation controller with a plurality ofreceptacles for each receiving a station module that is controlled bythe microprocessor to open and close at least one solenoid actuatedvalve operatively connected to the station module; inserting a moduleinto one of the receptacles; and manually gripping and moving a lockingmember mounted adjacent the receptacle from an UNLOCKED position to aLOCKED position to positively secure the station module in the adjacentreceptacle.